feat(topbar): the action follows the armed output; Test is an explicit ask again

Unit C (creator ruling 2026-11-12).

- Local MP4: one button, "Start Recording".
- YouTube: "Private Test Stream" beside "Review & Go Live", the latter with the primary face because it
  is the default ask.
- Running: "End Live Stream" (or "End Test" for a test run, "Stop Recording" for a local one).

The behavioural change underneath: SessionStartDecision.For no longer takes `editing`. Since 2026-10-30
EDIT silently chose test-vs-real, which meant the same button did two different things depending on a
toggle three inches away. With Test as its own button that inference has no job, so For() now reads only
the armed output and ON-AIR always means the real livestream. That supersedes the 2026-10-30 ruling;
SessionStartDecisionTests is rewritten to pin the new matrix rather than the old one.

A signed-out press still starts the sign-in flow instead of sitting dead (no-dead-ends), unchanged from
before — now stated in one place, the two new commands, instead of inside a route table.

680 pass, 0 warnings. Scope justification: Assets/starting-background.jpg is outside this unit — the
creator's replacement art, still awaiting their visual check.

Controls/TopBar.xaml

@@ -145,11 +145,19 @@
                 </Border>
                 <TextBlock Text="One output at a time" FontSize="11" VerticalAlignment="Center"
                            Foreground="{StaticResource Brush.OnSurfaceVariant}" Margin="8,0,0,0"/>
-                <!-- Go face names the world: "Start Recording" vs "Go Live".
-                     (Signed-out ON-AIR Start routes to the sign-in — StartSession.) -->
-                <Button Content="{Binding PrimaryStartButtonLabel}" Style="{StaticResource YtButton}"
-                        Height="32" Margin="10,0,0,0" Command="{Binding PrimaryStartCommand}"
-                        Visibility="{Binding ShowPrimaryStartButton, Converter={StaticResource BoolToVis}}"/>
+                <!-- The action follows the armed output (creator ruling 2026-11-12).
+                     MP4: one button. YouTube: the test run AND the real one, side by side — Test is
+                     something the creator asks for now, not something inferred from EDIT — with
+                     Review & Go Live carrying the primary face because it is the default ask. -->
+                <Button Content="Start Recording" Style="{StaticResource YtButton}"
+                        Height="32" Margin="10,0,0,0" Command="{Binding StartRecordingCommand}"
+                        Visibility="{Binding ShowStartRecordingAction, Converter={StaticResource BoolToVis}}"/>
+                <Button Content="Private Test Stream" Style="{StaticResource YtButtonSecondary}"
+                        Height="32" Margin="10,0,0,0" Command="{Binding TestStreamCommand}"
+                        Visibility="{Binding ShowYouTubeStartActions, Converter={StaticResource BoolToVis}}"/>
+                <Button Content="Review &amp; Go Live" Style="{StaticResource YtButton}"
+                        Height="32" Margin="8,0,0,0" Command="{Binding GoLiveCommand}"
+                        Visibility="{Binding ShowYouTubeStartActions, Converter={StaticResource BoolToVis}}"/>
                 <!-- TASK 32·3: the drop ended this broadcast. YouTube cannot resume a completed one, so
                      the only honest action is a new broadcast — one click, saved details, and the title
                      says it is a resume so the channel shows what happened. -->